Joseph Parker believes Sonny Bill Williams will return to boxing

Kiwi heavyweight champion Joseph Parker believes dual-code international Sonny Bill Williams will return to boxing one day.

The 32-year-old is unbeaten in his professional career with a 7-0 record but hasn't put on the gloves since January 2015, when he beat Chauncy Welliver.

Speaking to ESPN, Parker said he has been in contact recently with the All Blacks midfielder and feels Williams will return to the ring in the near future.

"Sonny is a great athlete, you know," Parker told ESPN.

"He's focused on his rugby at the moment and his family, but overall he's a great athlete. I think he'd love to get back into the ring but he's focusing on a few things for now.

Joseph Parker.
Joseph Parker. Photo credit: AAP

"One day he will come back and fight, but at the moment he's just concentrating on his family and rugby, but I think his passion for boxing is still there."

WBO champion Parker is currently in Las Vegas preparing for his upcoming unification title fight against Anthony Joshua for his IBF and WBA straps on April 1 (NZ time) at Cardiff's Principality Stadium.

Parker revealed that some All Blacks might make the trip from New Zealand to the United Kingdom for the fight.

"I think some of the players might be free and might come over," Parker added.

"I'm good friends with Jerome Kaino, Israel Dagg, Sonny Bill. I think if some of them do get time off they'll definitely come over and support.

"This is a fight where I think the whole of New Zealand are going to back us, and it can be a fight where we do well. It's going to put New Zealand boxing on the map and it's going to put us in the history books.

"As our team, we love a challenge. We love the challenge of fighting overseas. We love the challenge of fighting in front of 80,000 people so it's going to be an experience that everyone's going to come along for the ride and enjoy."